In Sinn’s book, which is centred on the early waves of Chinese migration to California through Hong Kong in the 19th century, she cites reasons uncovered through her studies of massive amounts of archives.

She said unlike those who were shipped to places such as Peru and Cuba where plantation owners paid for their journey, people who left for California did not have employers and bought their own boat tickets. These early gold prospectors also asked their families and relatives to join them.

“If it was so terrible, they would not have asked them to come,” she said. “The chain migration through family is a very important indication of how it was voluntary.”

Sinn spent more than a decade on the book before it was published in 2013. The Chinese-language edition came out in 2019.

Like her challenge of the coolie trade, Sinn uncovered other facts in her book to provide new perspectives on the historical movement of tens of thousands of Chinese men and women to the US state.

In particular, Sinn, a Hong Kong-born and educated scholar, focused on her hometown, which played a pivotal role as a transit point for both people and goods, and how the movement helped shape the city and built it into Asia’s Pacific gateway.

“This is not a book about Chinese in America,” she said. “My book is about movement – people moving back and forth, and Hong Kong’s role in facilitating this mobility.”

In 1848, a worker building Sutter’s Mill, a water-powered sawmill in Coloma, California, found gold in the nearby river, setting off a gold rush that would lure about 300,000 people from the rest of the country and abroad in the hunt for the precious metal.

Among the prospectors were Chinese migrants looking for opportunities abroad when living conditions deteriorated at home after the first opium war between 1839 and 1842, which forced the Qing dynasty to open five treaty ports and cede Hong Kong Island to Britain.

Sinn, an established author with several books under her belt, said beyond the first wave of Chinese migration in the late 1840s and early 1850s as part of the gold rush, a second wave occurred in the 1860s and 1870s to build railways in California. That was followed by a constant stream of people going there to do business, or find work with much better pay than back home. Most were from Guangdong province.

She said almost all of them left for California through Hong Kong, and also disembarked in the city on their way home, thanks to it being an “open port”, meaning people and goods flowed freely with no import and export duties, as well as relaxed regulations.

Sinn said steam and sailing ships were waiting off the port ready to take on passengers, and it was easy to sail straight across the Pacific Ocean to California, a journey that took 30 to 50 days.

After those migrants settled and formed families and communities in California, they looked for ways to get goods from their hometown sent over. Merchandise ranging from soy sauce, bird’s nests and shark fins to ink brushes and opium was shipped from Hong Kong to California.

“They desired good opium, Chinese clothes and shoes, and women. Hong Kong was placed to facilitate the flow of them,” she said.

Sinn described Hong Kong as an “in-between place”, whose role had been overlooked in previous migration studies which had focused only on starting points and destination countries. She said its role as a transit point was pivotal to the movement.

The booming shipping industry made the city more prosperous – there were more big trading companies, land value went up, and more people came to Hong Kong.

“The gold rush and the subsequent California trade … made Hong Kong into a first-rate international port,” she said.

Also among the shipments was a “strange article of export” – the remains of migrants who died in California before they could make a return journey to meet “their desire for being buried at home”, Sinn said.

She wrote in the book that an American ship, the Sunny South, left San Francisco for Hong Kong on May 15, 1855 with freight of 70 Chinese corpses, the first of many such shipments.

“One of the most important things that they sent back was their bones. When they died, they wanted to be buried in their home villages,” she said.

Hong Kong thus became not only the port of embarkation for the migrants, but also the port of disembarkation for those who returned, including the dead.

She said the repatriation of remains was a defining feature of the Chinese migration to California. Hong Kong, with its free movement of people and funds as well as peace and stability, made this possible.

Sinn said all of these provided a new perspective for people to look at the Chinese migration, as well as Hong Kong.

“It is a new way of looking at Hong Kong history,” said Sinn, who has a wide range of research interests including modern China, Hong Kong, culture and migration.

“I’m a Hong Kong historian. I want to tell people what kind of place Hong Kong is, and it helps realise what kind of person I am too.”